1. Field of the Invention
The present invention relates generally to medical apparatus and methods and more particularly to devices and methods for removal of unwanted tissue such as thrombus, atheroma, fluid, polyps, cysts or other obstructive matter from body lumens, such as blood vessels, ureters, bile ducts or fallopian tubes.
Currently, there are many clinical approaches to removing unwanted material, many of which are performed surgically, wherein the treatment site is accessed directly through a surgical incision.
In recent years, a variety of catheter devices have been developed for use in intraluminal and intravascular procedures for fragmentation and removal of obstructive matter, such as blood clots, thrombus, atheroma, and the like, from blood vessels. More recently, devices that can be inserted percutaneously through a puncture in the skin have been developed to make the procedures less invasive. For example, a catheter device is inserted into a blood vessel at an access site located some distance away from the intended treatment site, and is then advanced through the vessel lumen until the treatment site is reached. In most instances this approach is performed xe2x80x9cover-the-wire,xe2x80x9d a technique that requires the physician to first place a guidewire device into the vessel lumen over which a larger catheter device can be tracked.
These techniques may employ various devices to fragment the unwanted clot or tissue from blood vessels such as rotating baskets or impellers as described in U.S. Pat. Nos. 5,766,191 and 5,569,275, cutters as described in U.S. Pat. No. 5,501,694, and high pressure fluid infusion to create a Venturi effect as described in U.S. Pat. No. 5,795,322. Other devices rely on the principles of the Archimedes-type screw, such as a one-piece solid machined screw to break up and/or remove clot.
In many instances, the luminal treatment techniques include infusing the vessel or treatment site with fluid (saline or a thrombolytic agent) to assist in breaking up the clot or tissue into a particle size that can then be aspirated through a lumen of the treatment device or using a secondary catheter hooked up to a source of vacuum/suction. Depending on the method of fragmentation and the consistency of the clot or tissue, the particle size can vary. If the material is not thoroughly fragmented, the larger particles can build up in the catheter and block the aspiration lumen.
While these catheters and techniques have been fairly successful, there is a need for improved devices for more efficiently evacuating fragmented material from the vessel or body lumen in order to overcome the difficulties of continued fluid infusion and material build up that blocks the aspiration lumen. Furthermore, it would be desirable to have devices that allowed aspiration of larger particles of fragmented material, thereby reducing procedure time. Preferably, such improved devices will have a low profile to enable percutaneous use, and will be flexible and torqueable to enable their use in tortuous lumens. Furthermore, such devices will preferably be designed to be placed over a guidewire and will be structured to mechanically translate and transport the fragmented material by directly pumping it through the catheter shaft. Optionally, the devices should include mechanisms for infusing materials, such as thrombolytic and other therapeutic agents, as well as disrupting the occlusive materials.
At least some of these objectives will be met by the design and use of the present invention.
2. Description of the Background Art
U.S. Pat. No. 5,556,408 describes an atherectomy cutter employing a vacuum source for removal of loose stenotic material and other debris from a vessel. Removal of thrombus by a rotating core wire on a drive shaft is described in U.S. Pat. No. 5,695,507 and fragmentation and removal of tissue using high pressure liquid is described in U.S. Pat. No. 5,795,322. U.S. Pat. No. 4,923,462 describes a coiled wire coated with Teflon and used as a drive shaft to rotate a catheter. Furthermore, U.S. Pat. No. 5,334,211 describes a coiled guidewire used to stabilize an atherectomy device. Patents describing atherectomy catheters with rotating helical pumping elements in U.S. Pat. Nos. 4,732,154; 4,886,490; 4,883,458; 4,979,939; 5,041,082; 5,135,531; 5,334,211; 5,443,443; and 5,653,696. A rotary thrombectomy catheter having an inner helical blade is commercially available under the tradename Straub Rotarex(copyright) from Straub Medical AG, as described in a brochure with a copyright of August 1999. Use and construction of the Straub Rotarex(copyright) also appears to be described in Schmitt et al. (1999) Cardiovasc. Intervent. Radiol. 22: 504-509 and in U.S. Pat. Nos. 5,876,414 and 5,873,882. Other patents of interest include U.S. Pat. Nos. 4,737,153; 4,966,604; 5,047,040; 5,180,376; 5,226,909; 5,462,529; 5,501,694; 5,569,275; 5,630,806; 5,766,191, 5,843,031; 5,911,734; 5,947,940; and 5,972,019; as well as published PCT applications WO 99/56801; WO 99/56638; and WO 98/38929. Motor drive units for catheters and other devices are described in U.S. Pat. Nos. 4,771,774 and 5,485,042.
According to the present invention, improved apparatus and methods are provided for transporting material between a target site in a body lumen of a patient and a location external to the patient. In some cases, the materials will be transported from the target site to the external location, which methods will generally be referred to as aspiration. In other cases, the material may be transported from the external location to the target site within the body lumen, which methods will generally referred to as infusion. In still other cases, materials may be simultaneously transported from the external location to the internal target site and transported away from the internal target site to the external location, referred to as circulation. In all cases, the material transport will be enhanced by rotation of an impeller disposed in a lumen of a catheter. The impeller will usually comprise a tubular or solid shaft having a helical rotor extending at least partially over an exterior surface thereof. Thus, rotation of the impeller will pump the material in the manner of an xe2x80x9cArchimedes screw.xe2x80x9d
In addition to such mechanical pumping, the methods and apparatus of the present invention may rely on supplemental pressurization of the catheter lumen being used to transport the material. In particular, for infusion, the liquid or other material to be introduced may be supplied under pressure, typically in the range from 0.1 psi to 10,000 psi, usually in the range from 5 psi to 350 psi. Conversely, in the case of aspiration, a vacuum may be applied to the catheter lumen, usually from 1 mmHg to 760 mmHg, usually from 5 mmHg to 760 mmHg.
The methods and apparatus of the present invention will be particularly suitable for use in medical procedures for removing occlusive and other substances from body lumens, such as blood clots, thrombus, and the like, from blood vessels. Catheters according to the present invention will be suitable for percutaneous introduction or introduction by a surgical cutdown to the blood vessel or other body lumen. Usually, the catheters will then be advanced to a remote target site where the treatment is performed. Preferably, the catheters of the present invention will be introduced over a guidewire in a so-called xe2x80x9cover-the-wirexe2x80x9d technique, although use of a guidewire will not always be required. Optionally, the apparatus of the present invention may be used in conjunction with a variety of other interventional catheters, particularly for intravascular treatments. For example, the material transport catheters of the present invention may be used to infuse thrombolytic and other therapeutic agents and/or aspirate fragmented clot, thrombus, and other occlusive materials in conjunction with angioplasty, atherectomy, laser ablation, embolectomy, endarterectomy and other known intravascular interventions. In particular, the material transport catheters of the present invention may be used in the procedures described in copending application Ser. No. 09/454,517, which has previously been incorporated herein by reference.
In a first aspect of the present invention, an over-the-wire material transport catheter comprises a catheter body having a proximal end, a distal end, and a lumen therebetween. An impeller is rotatably disposed in the lumen of the catheter body, and the impeller includes a tubular shaft having a central guidewire lumen therethrough. A helical rotor extends at least partially over an exterior surface of the tubular shaft, and it is intended that the material transport catheter be introduced over a guidewire in a conventional manner. Moreover, the impeller will usually be rotated over the guidewire, i.e., while the guidewire remains in place in the central guidewire lumen of the impeller, during use of the catheter for aspiration and/or infusion. Optionally, the material transport catheter may further comprise a material capture device, such as a funnel structure, a macerator, or the like, at or near the distal end of the catheter body. Alternatively, the distal end of the catheter body may be substantially free from surrounding structure so that a desired material may be infused and/or aspirated directly through one or more ports in the catheter body at or near its distal end.
In a second aspect, a selective infusion-aspiration catheter constructed in accordance with the principles of the present invention comprises a catheter body having a proximal end, a distal end, and a lumen therebetween. An impeller is rotatably disposed in the lumen of the catheter body, and a driver is provided which is coupleable to the impeller. By xe2x80x9ccoupleable,xe2x80x9d it is meant either that the driver and impeller are permanently connected, or more usually, that the driver is a separate component but that the driver and impeller are adapted to selectively mate and permit the driver to rotate the impeller while the impeller remains disposed in the catheter body lumen. The driver will be adapted to selectively rotate the impeller in either a first direction to induce aspiration to the catheter body lumen or in a second direction to induce infusion through the catheter body lumen. In this way, the selective infusion-aspiration catheter can be used either for infusion or aspiration depending on the particular circumstances encountered. The selective infusion-aspiration catheter may further comprise a material capture device disposed at or near the distal end of the catheter body, such as a funnel structure, a macerator, or the like. Alternatively, the distal end of the catheter body may be substantially free from surrounding structure so that material may be aspirated and/or infused through one or more ports located at or near the distal end of the catheter body.
In a third aspect of the present invention, a circulation catheter comprises a catheter body having a proximal end, a distal end, and at least one lumen extending between the proximal end and the distal end. A first impeller is arranged in a lumen of a catheter body to aspirate materials from the distal end to the proximal end of the catheter body when the impeller is rotated. A second impeller is arranged in a lumen of the catheter body to infuse materials from the proximal end of the catheter body to the distal end of the catheter body when the second impeller is rotated. Since the circulation catheter includes two separate impellers, it is possible to rotate the impellers simultaneously so that material can be infused to a target location within a body lumen and simultaneously aspirated from that target location. For example, the circulation catheter may be used to introduce thrombolytic or other therapeutic agent to a blood vessel and to simultaneously or sequentially remove the lysed clot, thrombus, and other materials from the blood vessel. Suitable thrombolytic and other agents include GPIIIb/IIa antagonists, tissue plasminogen activator (tPA), calcium dissolving agents, urokinase (proUK), heparinized saline, and the like. Other therapeutic agents include fibrinolytics, anti-coagulants, antiplatlet drugs, anti-thrombin, gene therapy agents, chemotherapeutic agents, brachytherapy agents, and the like. Optionally, the first impeller and second impeller may terminate at spaced-apart ports along the length of the catheter body so that the thrombolytic or other agent will be assured of having a minimum residence time within the blood vessel prior to being aspirated. Further optionally, the first impeller and second impeller may be disposed in separate lumens within the catheter body. In such cases, both impellers will usually comprise a tubular or solid shaft having a helical rotor formed over the outer surface thereof. Rotation of the shaft thus selectively infuses or aspirates material through the associated catheter lumen. Alternatively, the first and second impellers may comprise a common tubular shaft where a first helical rotor is mounted over the exterior surface and a second helical rotor is mounted over an interior surface of the shaft lumen. By counterwinding the two helical rotors, it will be appreciated that the outer rotor will transport material in a first direction while the inner rotor transports the material in opposite direction. Thus, material may be infused through the annular lumen formed between the outside of the tubular shaft and the catheter body lumen and aspirated back through the interior of the tubular shaft, or vice versa.
As with the prior embodiments, the circulation catheter may further comprise a material capture device disposed at the distal end of the catheter body, such as a funnel structure, a macerator, or the like. Alternatively, the catheter body may be substantially free from surrounding structure.
In a fourth aspect of the present invention, a mechanical pump for use in a medical device comprises an elongate hollow, flexible inner tube having a proximal end, a distal end, and a central guidewire lumen. A first coiled (helical) rotor element having a distal end and a proximal end is disposed over an outer surface of the inner tube. A jacket secures the coiled rotor element to the outer surface to complete the mechanical pump. The mechanical pump structure may then be used in the lumen of a catheter body or elsewhere in order to provide a pumping action in the manner of an Archimedes screw.
Preferably, the inner tube has an outer diameter in the range from 0.5 mm to 5 mm, usually from 1 mm to 2 mm. The assembled coiled rotor will have a width in the diameter from 0.5 mm to 10 mm, preferably from 0.5 mm to 3 mm, and a pitch over the inner tube in the range from 1 turns/cm to 50 turns/cm, preferably from 3 turns/cm to 10 turns/cm. Optionally, the mechanical pump may further comprise a second coiled rotor element disposed over an inner surface of the central lumen of the inner tube. The first and second coiled rotors will usually be counterwound so that the pump may direct flow in both a distal direction and a proximal direction when the inner tube is rotated in a single direction. Alternatively, the first and second coiled rotors may be co-wound so that the pump may provide an increased flow through a catheter lumen when the pump is rotated in either direction. In a particular aspect of the present invention, a distal portion of the coiled rotor may be unattached to the outer surface of the inner tube so that said unattached portion forms or provides a xe2x80x9cwhipxe2x80x9d element as the pump is rotated. The whip element will be suitable for mechanically disrupting clot, thrombus, or other occlusive materials when the pump is rotated in a body lumen. Alternatively, the whip may be used to mix the thrombolytic or other agents (as set forth above) which are being introduced by the pump in a blood vessel or other body lumen.
The mechanical pump just described may be fabricated by providing a hollow flexible tube, placing a resilient coiled rotor over an outer surface of the tube, and forming a jacket over at least a portion of the outer surface of the tube. In this way, the coiled rotor is secured to the outer surface of the flexible tube. Such a fabrication method is inexpensive and provides a high quality product. Placing the resilient coil over an outer surface of the inner tube may comprise winding the coil over the surface to successively place individual turns of the coil as the inner tube is rotated. Alternatively, a pre-formed coil may be partially xe2x80x9cunwoundxe2x80x9d to increase its diameter and permit the coil to be located over the exterior surface of the inner tube. When in the proper location, the coil may be allowed to rewind over the surface to provide an interference fit. The interference fit can be enhanced by heating the wire. Preferably, the coil is then secured to the outer surface of the inner tube by forming or placing a jacket over the structure. For example, the jacket formed by dip coating the assembly of the tube and rotor(s) into an appropriate curable liquid polymer, such as nylon, polyurethane, polyimide, polyamide, PTFE, FEP, and the like. The coating can then be heated and/or radiation cured to induce cross-linking. Further, alternatively, the jacket may be placed by providing a heat shrinkable polymeric tube or sleeve, placing said tube or sleeve over the combination of inner tube and helical rotor, and then shrinking the jacket over the inner tube and coiled rotor to hold the two together. Further alternatively, the jacket may be formed by extruding a polymeric material directly over the inner tube and coil, or by vapor deposition or spray coating. In an alternative embodiment, the coil may be attached to the inner tube by an adhesive.
The present invention still further comprises methods for transporting materials between a target site in a body lumen of a patient in a location external to the patient. The distal end of the catheter is introduced to the target site over a guidewire. First impeller is rotated over the guidewire within a lumen in the catheter to transport material between the distal end of the catheter and a proximal end of the catheter. The material may be selectively transported in a first direction by rotating the impeller for aspiration, and a vacuum may be applied to the lumen of the catheter to assist in transporting material from the distal end. Alternatively, the impeller may be selectively rotated to transport material from the proximal end of the catheter through the catheter lumen to the distal end of the catheter, e.g., to infuse materials. In such instances, the materials may be provided to the catheter lumen under pressure to assist in transporting the material through the catheter lumen to the distal end of the catheter.
In some instances, the direction in which the impeller is rotated may be changed. Thus, at one time, the impeller may be rotated in a first direction to infuse materials to the target site within a body lumen. At a subsequent time, the impeller may be rotated in the opposite direction to remove or aspirate materials from the same target site.
In still another instance, a second impeller may be provided in the catheter and rotated to selectively transport material between the proximal end of the catheter and the distal end of the catheter. By simultaneously rotating the first impeller to transport material in an opposite direction, a circulation of material may be established.
In still another instance, first and second impellers may comprise counterwound helical rotors mounted on a common tubular member. In such an instance, rotation of the tubular member in one direction will cause a first rotor to infuse materials to the target site while the second rotor aspirates materials from the same target site. In all instances, infusion and aspiration may be assisted by applying pressure or a vacuum, as appropriate. The first impeller will conveniently be mounted on the outside of the tubular member, e.g., by any of the methods described above for placing a coiled rotor over a shaft member. The second impeller will usually be in the form of a helical rotor disposed within the lumen of the tubular member. The helical rotor may be xe2x80x9cwound downxe2x80x9d to assume a low profile, inserted into the tubular member lumen, and then allowed to unwind to provide an interference fit with the lumen wall. The coil may be further secured or attached to the lumen wall by any of the methods described above.
In still another aspect of the present invention, a method for selectively infusing and aspirating materials between a target site in a body lumen or patient and the location external to the patient, comprises introducing a distal end of the catheter to the target site. An impeller within the lumen of the catheter is rotated in a first direction to infuse material to the target site. Sequentially, the impeller is rotated in a second direction to aspirate material to the target site. Such infusion and aspiration can be particularly useful with the delivery of thrombolytic agents to blood vessels and the removal of lysed clot from those blood vessels.
In yet still another aspect of the present invention, a method for circulating materials through a target site in a body lumen of a patient comprises introducing a distal end of the catheter to the target site. A first impeller within the lumen of the catheter is rotated to transport material to the target site. A second impeller within a lumen of the catheter is rotated to transport material away from the target site. The first and second impellers may be located within separate lumens within the catheter, or alternatively, may be located within the same lumen within the catheter. In latter case, first and second impellers will usually comprise a flexible inner tube having a first helical rotor formed over an outer surface thereof and a second helical rotor formed over an inner luminal surface thereof. The first and second helical rotors are counterwound so that rotation of the inner tube in one direction will cause flow over the tube in a first direction and flow through the tube in the opposite direction.
In particular, the present invention provides an elongate mechanical pump component that can be used in an aspiration catheter as a stand alone device, or as part of the shaft construction of a therapeutic device to remove the material fragmented by the working end of the therapeutic device. The mechanical pump component is hollow, forming a guidewire lumen to allow it to be compatible with use over a guidewire, or with devices requiring a guidewire.
In an exemplary embodiment the pump device is formed from a resilient wire coil, wound along the length of a hollow flexible polymer tube, and bonded or attached thereto by an outer polymer coating that cross links or heat bonds to the inner tube. The coil member can be of various geometric cross sectional shapes. The outer polymer coating is preferably made of a thinner wall plastic than the inner hollow tube to assist in the attachment process. The thin wall coating also allows the struts of the coil member to protrude from the surface of the inner tube which, when rotated, provide the pumping action.
The present invention may also incorporate an outer sheath surrounding the mechanical pump to form a catheter device. The catheter device would be attached to a rotating motor drive unit (MDU) at the proximal end allowing the mechanical pump component to rotate at varying speeds, while the catheter sheath remains stationary. Optionally, the MDU can selectively drive the pump element in a clockwise or counterclockwise direction relative to the longitudinal axis of the device. In use, any material to be removed is evacuated through the annular space between the mechanical pump and the outer sheath and is moved proximally by the rotating coils of the mechanical pump.